Can I refresh 10g of discard sourdough starter and use for the pizza dough?

So I'm in the process of making my sourdough starter, day 25. And I have my discard starter in the refrigerator. Can I take 10 grams of the discard, add the ingredients to make the leaven, and leave in a bowl on the counter to begin making the pizza dough?

Also, my grocery store has not had whole wheat flour for weeks. I have all purpose flour, spelt flour, and einkorn flour, which one should I use instead of whole wheat?